Skill 15.4 Analyzing heating and cooling curves

When the system is heated, energy is transferred into it. In response to the energy it receives, the system changes, either by increasing its temperature or changing phase. 

During the interval marked A on the graph below, energy is being absorbed by the water molecules to increase the temperature to water s melting point, 0° C. The slope of the line for this interval shows the increase in temperature and is related to the heat capacity of the substance. 

Temperature again increases during interval C on the graph. Energy is being absorbed by the liquid water molecules. Notice that the slope of the line during this interval is different than the slope of the line during interval A. This is due to differences in the heat capacity of ice and liquid water. 

---